When a client requests a resource without using credentials, the server challenges the request and indicates what authentication schemes it supports. The client chooses an authentication scheme and sends the appropriate WWW-authenticate header to the server. When WebClientProtocol.PreAuthenticate is true, the WWW-authenticate header is sent with all subsequent requests.

When WebClientProtocol.PreAuthenticate is false, a request is made to the XML Web service method without initially attempting to authenticate the user. If the XML Web service allows anonymous access, then the XML Web service method is executed. If anonymous access is disallowed, a 401 HTTP return code is sent back to the client. In response, the System.Web.Services.Protocols.WebClientProtocol class returns authentication credentials to the Web server. If the client is authenticated and subsequently authorized to access the XML Web service, the XML Web service method is executed; otherwise the client is denied access.

Namespace: System.Web.Services.Protocols
Assembly: System.Web.Services (in System.Web.Services.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0